There are two popular brands of metal clay, Precious Metal Clay
(PMC) and Art Clay Silver (ACS). You can choose whichever you like,
as they are both used in the same way. However it’s useful to know a
bit about how they came about and what’s the difference between
products in their range.

Precious Metal Clay or PMC was developed in the early 1990s in Japan
by metallurgist Dr. A. Morikawa, who worked for Mitsubishi. The
material consists of extremely fine precious metal powder and a
water-soluble organic binder which burns off during firing. Success
was first achieved with gold, and later duplicated with silver, PMC
Original, which had to be fired in a kiln and had a very high
shrinkage rate. Mitsubishi Materials Corporation later developed two
additional versions of silver called PMC+, which displays less
shrinkage, and PMC3, which fires at lower temperatures in a kiln or
by using a torch. A 22k gold coating material (Aura 22), and a 22k
yellow gold alloy are also manufactured. PMC also manufacures an 18k
gold clay and a platinum clay, but these latter two are only
marketed in Japan.

Art Clay or ACS was developed by AIDA Chemical Industries. Art Clay
followed PMC Original with their Art Clay Original clay, which
allowed the user to use a handheld torch or gas hob for firing. The
clay also shrank less, only 8-10%.

Further developments introduced the Art Clay Slow Dry, a clay with a
longer working time. Art Clay 650 and Art Clay 650 Slow Dry soon
followed - both clays that can be fired as low as 650C, allowing the
user to combine the clay with glass and sterling silver which had
previously been affected by the higher temperature needed to fire
the previous clays. AIDA also manufacturers Oil Paste, a product
only used on fired metal clay, and Overlay Paste, which is designed
for drawing designs on glass and porcelain.

In 2006 AIDA also introduced the Art Clay Gold Paste, a more
economical way to work with gold. The paste is painted onto the
fired silver clay, then refired in a kiln, or with a torch or gas
stove. When fired it bonds with the silver, giving a 22ct gold
accent. The same year also saw Art Clay Slow Tarnish introduced, a
clay which tarnishes less rapidly than the other metal clays.

All courses give you expert video and written tuition, personal
feedback, advice from industry insiders and opportunities to share
your work on a wider scale. You’ll also get exclusive access to our
Mastered Meets series of webinars which feature leading jewellery
experts.

This is one of the best sources for info on metal clay, very
thorough, covering all brands and formulas. This is not a school
either actual or virtual. I know its name includes the word
"academy", but it is just a free encyclopedic collection of
well-researched including free tutorials,
workshop/school listings, etc. You will find out almost everything
you need to know about using metal clays on this site.